Extrusion process are known for the production of a variety of structural shapes, sections and profiles of thermoplastic materials, such as polyvinylchloride. Among the structural shapes, sections or profiles produced by extrusion are window-forming profiles, window frame members, door frame members, siding and the like.
An extruded material emerges from an extrusion die after having been plastified, masticated and mixed at elevated temperatures in a worm-type extruder with at last one screw and generally at least two screws, at an elevated temperature so that cooling of the extrusion is required.
While air cooling is possible, the amount of heat which can be abstracted from the extrusions by air cooling processes is limited so that significant cooling stretches are required.
Conventional water cooling techniques, whereby water is simply sprayed on the extruded profile have been found to be uneconomical and of low energy efficiency.